21551322544121 has 2 divisors, whose sum is σ = 21551322544122. Its totient is φ = 21551322544120.

The previous prime is 21551322544097. The next prime is 21551322544127. The reversal of 21551322544121 is 12144522315512.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 21016173235600 + 535149308521 = 4584340^2 + 731539^2 .

It is a cyclic number.

It is not a de Polignac number, because 21551322544121 - 2¹⁴ = 21551322527737 is a prime.

It is not a weakly prime, because it can be changed into another prime (21551322544127) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (29) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10775661272060 + 10775661272061.

It is an arithmetic number, because the mean of its divisors is an integer number (10775661272061).

Almost surely, 2^{21551322544121} is an apocalyptic number.

It is an amenable number.

21551322544121 is a deficient number, since it is larger than the sum of its proper divisors (1).

21551322544121 is an equidigital number, since it uses as much as digits as its factorization.

21551322544121 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 96000, while the sum is 38.

Adding to 21551322544121 its reverse (12144522315512), we get a palindrome (33695844859633).

The spelling of 21551322544121 in words is "twenty-one trillion, five hundred fifty-one billion, three hundred twenty-two million, five hundred forty-four thousand, one hundred twenty-one".